fsi: occ: Use a large buffer for responses

Allocate a large buffer for each OCC to handle response data. This
removes memory allocation during an operation, and also allows for
the maximum amount of SBE FFDC.

Previously for the putsram and attn commands, only 32 words would have
been available, and for getsram, only up to the size of the transfer.
SBE FFDC might be up to 8Kb.

The SBE interface expects data to be specified in units of words (4
bytes), defined as OCC_MAX_RESP_WORDS.

This change allows the full FFDC capture to be implemented, where before
it was not available.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20211019205307.36946-2-eajames@linux.ibm.com
Signed-off-by: Joel Stanley <joel@jms.id.au>

1 files changed, 44 insertions, 66 deletions

diff --git a/drivers/fsi/fsi-occ.c b/drivers/fsi/fsi-occ.c
index ecf738411fe2..b4302776026d 100644
--- a/drivers/fsi/fsi-occ.c
+++ b/drivers/fsi/fsi-occ.c
@@ -10,6 +10,7 @@
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/miscdevice.h>
+#include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/fsi-occ.h>
@@ -33,13 +34,6 @@
 
 #define OCC_P10_SRAM_MODE	0x58	/* Normal mode, OCB channel 2 */
 
-/*
- * Assume we don't have much FFDC, if we do we'll overflow and
- * fail the command. This needs to be big enough for simple
- * commands as well.
- */
-#define OCC_SBE_STATUS_WORDS	32
-
 #define OCC_TIMEOUT_MS		1000
 #define OCC_CMD_IN_PRG_WAIT_MS	50
 
@@ -51,6 +45,7 @@ struct occ {
 	char name[32];
 	int idx;
 	u8 sequence_number;
+	void *buffer;
 	enum versions version;
 	struct miscdevice mdev;
 	struct mutex occ_lock;
@@ -241,8 +236,10 @@ static int occ_verify_checksum(struct occ *occ, struct occ_response *resp,
 static int occ_getsram(struct occ *occ, u32 offset, void *data, ssize_t len)
 {
 	u32 data_len = ((len + 7) / 8) * 8;	/* must be multiples of 8 B */
-	size_t cmd_len, resp_len, resp_data_len;
-	__be32 *resp, cmd[6];
+	size_t cmd_len, resp_data_len;
+	size_t resp_len = OCC_MAX_RESP_WORDS;
+	__be32 *resp = occ->buffer;
+	__be32 cmd[6];
 	int idx = 0, rc;
 
 	/*
@@ -269,19 +266,19 @@ static int occ_getsram(struct occ *occ, u32 offset, void *data, ssize_t len)
 	cmd[1] = cpu_to_be32(SBEFIFO_CMD_GET_OCC_SRAM);
 	cmd[4 + idx] = cpu_to_be32(data_len);
 
-	resp_len = (data_len >> 2) + OCC_SBE_STATUS_WORDS;
-	resp = kzalloc(resp_len << 2, GFP_KERNEL);
-	if (!resp)
-		return -ENOMEM;
-
 	rc = sbefifo_submit(occ->sbefifo, cmd, cmd_len, resp, &resp_len);
 	if (rc)
-		goto free;
+		return rc;
 
 	rc = sbefifo_parse_status(occ->sbefifo, SBEFIFO_CMD_GET_OCC_SRAM,
 				  resp, resp_len, &resp_len);
-	if (rc)
-		goto free;
+	if (rc > 0) {
+		dev_err(occ->dev, "SRAM read returned failure status: %08x\n",
+			rc);
+		return -EBADMSG;
+	} else if (rc) {
+		return rc;
+	}
 
 	resp_data_len = be32_to_cpu(resp[resp_len - 1]);
 	if (resp_data_len != data_len) {
@@ -292,39 +289,21 @@ static int occ_getsram(struct occ *occ, u32 offset, void *data, ssize_t len)
 		memcpy(data, resp, len);
 	}
 
-free:
-	/* Convert positive SBEI status */
-	if (rc > 0) {
-		dev_err(occ->dev, "SRAM read returned failure status: %08x\n",
-			rc);
-		rc = -EBADMSG;
-	}
-
-	kfree(resp);
 	return rc;
 }
 
 static int occ_putsram(struct occ *occ, const void *data, ssize_t len,
 		       u8 seq_no, u16 checksum)
 {
-	size_t cmd_len, buf_len, resp_len, resp_data_len;
 	u32 data_len = ((len + 7) / 8) * 8;	/* must be multiples of 8 B */
-	__be32 *buf;
+	size_t cmd_len, resp_data_len;
+	size_t resp_len = OCC_MAX_RESP_WORDS;
+	__be32 *buf = occ->buffer;
 	u8 *byte_buf;
 	int idx = 0, rc;
 
 	cmd_len = (occ->version == occ_p10) ? 6 : 5;
-
-	/*
-	 * We use the same buffer for command and response, make
-	 * sure it's big enough
-	 */
-	resp_len = OCC_SBE_STATUS_WORDS;
 	cmd_len += data_len >> 2;
-	buf_len = max(cmd_len, resp_len);
-	buf = kzalloc(buf_len << 2, GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
 
 	/*
 	 * Magic sequence to do SBE putsram command. SBE will transfer
@@ -361,12 +340,17 @@ static int occ_putsram(struct occ *occ, const void *data, ssize_t len,
 
 	rc = sbefifo_submit(occ->sbefifo, buf, cmd_len, buf, &resp_len);
 	if (rc)
-		goto free;
+		return rc;
 
 	rc = sbefifo_parse_status(occ->sbefifo, SBEFIFO_CMD_PUT_OCC_SRAM,
 				  buf, resp_len, &resp_len);
-	if (rc)
-		goto free;
+	if (rc > 0) {
+		dev_err(occ->dev, "SRAM write returned failure status: %08x\n",
+			rc);
+		return -EBADMSG;
+	} else if (rc) {
+		return rc;
+	}
 
 	if (resp_len != 1) {
 		dev_err(occ->dev, "SRAM write response length invalid: %zd\n",
@@ -382,27 +366,16 @@ static int occ_putsram(struct occ *occ, const void *data, ssize_t len,
 		}
 	}
 
-free:
-	/* Convert positive SBEI status */
-	if (rc > 0) {
-		dev_err(occ->dev, "SRAM write returned failure status: %08x\n",
-			rc);
-		rc = -EBADMSG;
-	}
-
-	kfree(buf);
 	return rc;
 }
 
 static int occ_trigger_attn(struct occ *occ)
 {
-	__be32 buf[OCC_SBE_STATUS_WORDS];
-	size_t cmd_len, resp_len, resp_data_len;
+	__be32 *buf = occ->buffer;
+	size_t cmd_len, resp_data_len;
+	size_t resp_len = OCC_MAX_RESP_WORDS;
 	int idx = 0, rc;
 
-	BUILD_BUG_ON(OCC_SBE_STATUS_WORDS < 8);
-	resp_len = OCC_SBE_STATUS_WORDS;
-
 	switch (occ->version) {
 	default:
 	case occ_p9:
@@ -427,12 +400,17 @@ static int occ_trigger_attn(struct occ *occ)
 
 	rc = sbefifo_submit(occ->sbefifo, buf, cmd_len, buf, &resp_len);
 	if (rc)
-		goto error;
+		return rc;
 
 	rc = sbefifo_parse_status(occ->sbefifo, SBEFIFO_CMD_PUT_OCC_SRAM,
 				  buf, resp_len, &resp_len);
-	if (rc)
-		goto error;
+	if (rc > 0) {
+		dev_err(occ->dev, "SRAM attn returned failure status: %08x\n",
+			rc);
+		return -EBADMSG;
+	} else if (rc) {
+		return rc;
+	}
 
 	if (resp_len != 1) {
 		dev_err(occ->dev, "SRAM attn response length invalid: %zd\n",
@@ -448,14 +426,6 @@ static int occ_trigger_attn(struct occ *occ)
 		}
 	}
 
- error:
-	/* Convert positive SBEI status */
-	if (rc > 0) {
-		dev_err(occ->dev, "SRAM attn returned failure status: %08x\n",
-			rc);
-		rc = -EBADMSG;
-	}
-
 	return rc;
 }
 
@@ -590,6 +560,11 @@ static int occ_probe(struct platform_device *pdev)
 	if (!occ)
 		return -ENOMEM;
 
+	/* SBE words are always four bytes */
+	occ->buffer = kvmalloc(OCC_MAX_RESP_WORDS * 4, GFP_KERNEL);
+	if (!occ->buffer)
+		return -ENOMEM;
+
 	occ->version = (uintptr_t)of_device_get_match_data(dev);
 	occ->dev = dev;
 	occ->sbefifo = dev->parent;
@@ -625,6 +600,7 @@ static int occ_probe(struct platform_device *pdev)
 	if (rc) {
 		dev_err(dev, "failed to register miscdevice: %d\n", rc);
 		ida_simple_remove(&occ_ida, occ->idx);
+		kvfree(occ->buffer);
 		return rc;
 	}
 
@@ -640,6 +616,8 @@ static int occ_remove(struct platform_device *pdev)
 {
 	struct occ *occ = platform_get_drvdata(pdev);
 
+	kvfree(occ->buffer);
+
 	misc_deregister(&occ->mdev);
 
 	device_for_each_child(&pdev->dev, NULL, occ_unregister_child);